Add the answer of Exercise 1.3.33

1-Fundamentals/1-3-BagsQueuesStacks/Ex_1_3_33_Deque.java

@@ -0,0 +1,86 @@
+/*
+ * 1.3.33 Deque. A double-ended queue or deque (pronounced “deck”) is like a stack or 
+ * a queue but supports adding and removing items at both ends. 
+ */
+public class Deque<Item> {
+	private class Node {
+		Node previous;
+		Node next;
+		Item item;
+	}
+
+	private Node Left; //the leftmost item of the queue
+	private Node Right; // the rightmost item of the queue
+	private int N;
+
+	Deque (){ //constructor,create an empty deque
+		Left = null;
+		Right = null;
+		N = 0;		
+	}	
+	public boolean isEmpty(){ //is the deque empty?
+		return N == 0;
+	}
+	public int size(){ //number of items in the deque
+		return N;
+	}
+	public void pushLeft(Item item) { //add an item to the left end
+		Node oldLeft = Left;
+		Left = new Node();
+		Left.item = item;
+		Left.previous = null;
+		if (isEmpty()){
+			Right = Left;
+		}else{
+			Left.next = oldLeft;
+			oldLeft.previous = Left;
+		}
+		N++;
+	}
+	public void pushRight(Item item){ //add an item to the right end
+		Node oldRight = Right;
+		Right = new Node();
+		Right.item = item;
+		Right.next = null;
+		if (isEmpty()){
+			Left = Right;
+		}else{
+			oldRight.next = Right;
+			Right.previous = Right;
+		}
+		N++;
+	}
+	public Item popLeft(){ //remove an item from the left end
+		if (isEmpty()){
+			return null;
+		}else{
+			Item item = Left.item;
+			Left = Left.next;
+			N--;
+			if(isEmpty()){
+				Right = null;
+			}else {
+				Left.previous = null;
+			}
+			return item;
+		}
+	}
+	public Item popRight(){ //remove an item from the right end
+		if (isEmpty()){
+			return null;
+		}else{
+			Item item = Right.item;
+			Right = Right.next;
+			N--;
+			if(isEmpty()){
+				Left = null;
+			}else {
+				Right.next = null;
+			}
+			return item;
+		}
+	}
+
+
+
+}

1-Fundamentals/1-3-BagsQueuesStacks/Ex_1_3_33_ResizingArrayDequue.java

@@ -0,0 +1,62 @@
+/*
+ * Write  a class ResizingArrayDeque that uses a resizing array to implement this API.
+ */
+public class ResizingArrayDequue<Item> {
+	private Item[] a;
+	private int N =0;
+	ResizingArrayDequue(){ //constructor
+		a = (Item[]) new Object[1];
+	}
+	public boolean isEmpty(){
+		return N == 0;
+	}
+	public int size(){
+		return N;
+	}
+	private void resize(int max){
+		Item[] temp = (Item[]) new Object[max];
+		for (int i = 0;i <N;i++){
+			temp[i] = a[i];
+		}
+		a =temp;
+	}
+	public void pushLeft(Item item){
+		if (N == a.length){
+			resize(a.length*2);
+		}
+		Item[] temp = (Item[]) new Object[a.length+1];
+		temp[0] = item;
+		for (int i = 1;i<a.length+1;i++){
+			temp[i] = a[i-1];
+		}
+		a = temp;
+		N++;
+	}
+	public void pushRight(Item item){
+		if (N == a.length){
+			resize(a.length*2);
+		}
+		a[N++] = item;
+	}
+	public Item popLeft(){
+		Item item = a[0];
+		Item[] temp = (Item[]) new Object[a.length-1];
+		for (int i = 0;i<a.length;i++){
+			temp[i] = a[i+1];
+		}
+		a = temp;
+		if(N > 0 && N == a.length/4){
+			resize(a.length/2);
+		}
+		N--;
+		return item;
+	}
+	public Item popRight(){
+		Item item = a[--N];
+		a[N] = null;
+		if(N > 0 && N == a.length/4){
+			resize(a.length/2);
+		}
+		return item;
+	}
+}